Acccording to the structures,the cartridge heater have two different style:inner lead and outer wiring.
1.We can see the difference according to the real picture as below:
2.Production process
Outer wiring: the terminal rod and lead wire are connected outside the heating tube through the crimping terminal.
Inner lead: The high temperature lead wire is directly drawn from inside the pipe port.
3.The material for the high temerature lead wire is different
External wiring: because the high temperature lead is welded externally with the lead rod, the temperature of the welding part will not be too high at this time. The high temperature lead of the external wiring can generally withstand 200 degrees.
Inner lead: the temperature of the lead wire reach at least 800 degrees. Generally, pure nickel wire is used, so the cost is high.
4.The creepage distance is different
From the perspective of creepage phenomenon, the inner lead wire is safer, and the two lead rods of the outer connection are insulated with glass fiber sleeve. If the two lead wires are accidentally expired, there will be hidden trouble of connecting.
5.Production efficiency
The production efficiency of the inner lead is far less than the outer wire, especially in welding inner lead and resistance wire, the process is more difficult, so the length of the inner lead wire should not be too long.
